What Does Inert Mean?
In horticulture, inert may refer to matter that is found in soil-less media, seed packages, fertilizers or pesticides. In general it relates to any material that is devoid of nutrients or active ingredients and are generally included to add structure, substance or as a carrier for the desired product. The percentage of inert matter in a horticultural product may also dictate its price or quality.
Some products such as certified seed are required by law to have established thresholds of inert material. With seeds, generally the less inert material, the higher the quality. In other instances, inert materials are critical for proper application rates such as with fertilizers or pesticides.